LANL, Los Alamos, New Mexico
For national security, it is important to detect the presence of Special Nuclear Materials (SNM), especially Highly-Enriched Uranium (HEU). Generally used methods for such detection include interrogation by photons and neutrons. For example, photofission in HEU can be initiated with 14-MeV photons. The resulting delayed neutrons and photons from the fission fragments are clear signatures of the presence of HEU. One can generate high-energy photons using electron accelerators via various mechanisms. In this paper, we will describe two of them, namely electron bremsstrahlung and Compton-backscattered photons. We focus on these two mechanisms because they cover a wide range of accelerator requirements. Electron bremsstrahlung can be generated using a compact low-energy electron linac while the generation of Compton-backscattered photons requires a high-energy electron accelerator of a few hundred MeV. We review these two options, describe their accelerator requirements, and compare their relative merits.
